by an NSF Shared Instrumentation Grant and 40% were 'matching" funds from the Salk Institute. In the past year, funds were obtained by Chris Kintnerto purchase a Biorad confocal fitted on an inverted Zeiss microscope. We have both confocal systems in a dedicated room specifically designed to house the confocal facility. This facility is centrally located within the East wing of MNL, immediately adjacent to the labs of Goulding, Lemke and O'Leary, and a short walk from the Pfaff lab. These systems, particularly the Zeiss system, are very heavily used by all of the labs of the program, and our work is completely dependent upon this microscopy. We have also obtained an additional computer workstation with similar software packages (and keys!) that allow for image analysis freeing the computer systems directly operating the confocal microscopes for image acquisition. We also have dedicated laboratory space assigned to the second component of the core - a facility for the analysis of gene expression. This facility includes space for warming trays, an embedding station, perfusion equipment, and incubators for in situ hybridizations and immunohistochemistry of whole embryos, dissected tissues, and sections (slides). A storage facility and log for cDNA and antibody reagents frequently used by all component laboratories of the program project will also be housed in the Analytical core, and managed by the core technician. Dennis O'Leary (5% effort) will supervise the operation of the Analytical Core, which will be directly managed by an experienced technician, Ms. Berta Higgins (50% effort), who has the management skills and experience appropriate for this position. This technician's responsibilities include: 1. Management and supervision of a central facility for confocal and conventional microscopy. This room contains the microscopes, bench and shelf space, and computers for the support of an LSM 510 confocal microscope that is outfitted with both Ar/Kr (488nm and 568nm) and HeNe2 (633nm) lasers. The u.v. laser and an u.v. scan head for the confocal were purchased with a funding supplement to the program project obtained from a one-time NINDS equipment grant program several years ago. This part of the core will accommodate individual users from component projects in addition to the core technician, who will help operate the microscope, maintain equipment, update software for image analysis, manage data storage, organize time for individual members of the component labs to use the facility, schedule and oversee service contract maintenance, and importantly, train personnel in the proper use and care for this sophisticated, costly, and delicate equipment. 2. Management of a core facility for the analysis of gene expression. The bench space for this facility is also centrally located (immediately outside of the room that houses the confocal microscopes), in a broad corridor space that connects the Lemke, Goulding and O'Leary labs. These benches were previously used for manual DMAsequencing, and are therefore adjacent to a hood now used for histological procedures. The facility includes space for warming trays, an 248